Method and Device for Correcting Position Error

ABSTRACT

A method and the device for position detection are disclosed. The device comprises a plurality of strips intersecting each other to form a plurality of intersecting regions. A pair of depressed strips intersecting on an intersecting region contact to each other on a contact point to form a depressed intersecting region. According to the voltages of each strip before and after the strip is depressed, an error ratio can be determined. Based on the error ration, the position error caused by the contact impedance crossover strips can be corrected.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/761,930, filed Apr. 16, 2010, which claims the benefit of U.S.Provisional Application No. 61/301,661, filed on Feb. 5, 2010, andProvisional Application No. 61/245,063, filed on Sep. 23, 2009, whichare herein incorporated by reference for all intents and purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and device for positiondetection, and more particularly, to a method and device for depressedposition detection.

2. Description of the Prior Art

In U.S. Patent Application Publication No. 2007/0198926, Jouget et al.discloses a device for detecting position, which includes an upperelectrode layer and a lower electrode layer. The upper and lowerelectrode layers include a plurality of conductive stripes arranged inparallel in different directions. The upper and lower electrode layersare separated from each other by insulating spacers interposedtherebetween. The conductive stripes of the upper electrode layer aresequentially driven, and while each of the conductive stripes of theupper electrode layer is being driven, all conductive stripes in thelower electrode layer will be sequentially sensed once, thereby allintersecting points intersected by the stripes in the upper and lowerelectrode layers can be detected. In other words, when a stripe in theupper electrode layer being driven and a stripe in the lower electrodelayer being sensed are depressed and made to contact each other, currentflows from the driven stripe of the upper electrode layer to the sensedstripe of the lower electrode layer. By sensing signals in the stripesof the lower electrode layer, intersecting points that are depressed canbe detected.

As shown in FIG. 1, when a finger depresses a surface, a plurality ofintersecting points may be depressed simultaneously. During detection,signals in stripes of the lower electrode layer that are sensed laterwill be smaller. Thus, a different comparison value has to be used fordifferent intersecting points in order to correctly determinedepressions. However, this approach may still be not accurate enoughwhen the number of depressed intersecting points is large. Theestablishment and storage for the comparison values for eachintersecting point are clearly costly and not accurate enough. Inaddition, when higher resolution is demanded, the density of stripesneeds to be increased, and in turn the sensing frequency needs to belowered.

As can be seen, there are several shortcomings and inconvenience in theprior art requiring solutions that are not yet provided by any currentmethods and structures. Thus, a new technique is called for to addressthese long-standing problems.

SUMMARY OF THE INVENTION

In the light of forgoing drawbacks, a first objective of the presentinvention is to provide a method and device for position detection. Thedevice for position detection may include: a sensor including aplurality of conductive stripes constituting a plurality of intersectingregions, wherein a pair of depressed conductive stripes intersected inan intersecting region form a contact point due to electrical contact soas to define a depressed intersecting region; a driver for providing ahigh potential and a low potential; a detector for detecting a signal ofat least one conductive stripe; a selector for operatively coupling theconductive stripes with the driver and the detector; and a controllerfor controlling the driver, the detector and the selector to perform atleast the following operations: directly or indirectly via an extensionresistor respectively providing high and low potentials to a first endand second end of the same conductive stripe; directly or indirectly viaan extension resistor respectively providing high and low potentials toa first end of at least a first conductive stripe and a first end of atleast one second conductive stripe; detecting the signal between one ofthe conductive stripes and the extension resistor; and when high and lowpotentials are provided to one of a pair of depressed conductivestripes, potentials of one or both ends of first and second ends of theother one of the pair of depressed conductive stripes are detected; andwhen high and low potentials are respectively provided to the first andthe second ends of the same conductive stripe via the extensionresistor, a non-depressed potential and a depressed potential aredetermined based on the signal between the conductive stripe and theextension resistor.

The intersecting conductive stripes are spaced apart by a plurality ofspacers, when the conductive stripes are not depressed, they areelectrically insulated, and when depressed, they form a depressedintersecting region.

In the device for position detection, the method for position detectionmay include first detecting depressed intersecting regions, and thendetecting contact points on the depressed intersecting regions based onthe depressed intersecting regions. The detection of the depressedintersecting regions may include first detecting depressed conductivestripes, and then determining potentially depressed intersecting regionsbased on the depressed conductive stripes, and finally detectingdepressed intersecting regions from the potentially depressedintersecting regions.

Through the detection of depressed conductive stripes, the search fordepressed intersecting regions can be narrowed. Through the detection ofdepressed intersecting regions, the search for contact points can benarrowed. Thus, the method and device for position detection of thepresent invention can speed up the detection of all contact points. Theposition of each contact point can be expressed by two-dimensionalcoordinates.

Since the present invention adopts wider conductive stripes, thedetection range of these conductive stripes cover a larger range thanthe prior art, thus rendering a higher resolution.

In addition, the present invention is capable of detecting contactpoints of multiple different objects and tracing subsequent depressionsto determine different gestures.

A second objective of the present invention is to provide a method anddevice for determining total contact impedance of depressions. Saiddevice for position detection of the present invention further includes:determining each depression on the intersecting regions and totalcontact impedance for each depression, wherein the total compactimpedance for a depression that crosses intersecting regions is theparallel impedance of contact impedances of the plurality ofintersecting regions.

Said controller further includes tracing subsequent depressions of eachdepression based on the total compact impedance of each depression,wherein the differences of total compact impedances of each depressionand its each subsequent depression will be within a predetermine range,and the depressed intersecting regions corresponding to the samedepression will be neighboring intersecting regions.

Based on total contact impedances, depressions made by a pen, a fingeror a palm can be determined.

When total contact impedance is smaller than a threshold value, it isdetermined that there are multiple depressions on a set of neighboringdepressed intersecting regions, otherwise, there is a single depressedintersecting region.

A third objective of the present invention is to provide a method anddevice for determining contact impedance based on position. In saiddevice for position detection of the present invention, contactimpedance is determined based on the potential at the contact point ofone and the other of a pair of conductive stripes in a depressedintersecting region or the position of the intersecting region.

In the present invention, the contact impedance can be determined basedon the position of contact points or intersecting regions. The priorgives more accurate contact impedance; the latter can determineapproximate contact impedance before contact points are known,eliminating the need for detecting the locations of contact points to beomitted, thereby increasing efficiency. In addition, given that thecontact point or intersecting region is known, contact impedance can bedetermined by simply determining the potential at the contact point ofthe one and the other of the depressed conductive stripes without theneed to detect other signals.

The objectives of the present invention can be achieved by the followingtechnical measures. Based on said method and device for determiningcontact impedance of the present invention, the determination of thecontact impedance by the controller includes: determining a firstdimensional location and a second dimensional location of the contactpoint/intersecting region, and determining a first dimensional impedanceand a second dimensional impedance based on the first dimensionallocation and the second dimensional location; when providing high andlow potentials to one and the other of a pair of conductive stripes,detecting a first contact potential and a second contact potential ofone and the other of the pair of conductive stripes at the contactpoint/intersecting region; and determining the contact impedance,wherein the contact impedance is (R1+R2)/(((VH−VL)/(P1−P2))−1), whereinR1, R2, VH, VL, P1, and P2 are the first dimensional impedance, thesecond dimensional impedance, the high potential, the low potential, thefirst contact potential, and the second contact potential, respectively.

A fourth objective of the present invention is to provide a method anddevice for position detection with a palm omission function. In saiddevice for position detection of the present invention, the controllerfurther includes determining depressions to be omitted from alldepressions, wherein the total contact impedance of a depression to beomitted is smaller than a predetermined threshold value.

The present invention can therefore categorize each depression intodepression made by a pen, a finger or a palm based on the total contactimpedance, omitting those made by the palm. Thus, there is no need tosuspend the palm in the air while writing.

A fifth objective of the present invention is to provide a method anddevice for correction positional error. In said device for positiondetection of the present invention, when a conductive stripe hasparallel impedance due to a depression that crosses conductive stripeson the same layer, the position of the contact point detected willdeviate towards the depression that crosses the conductive stripes onthe same layer, causing error. The error correction of the presentinvention can correct this error and determine the true location of thedepression.

The objectives of the present invention can be achieved by the followingtechnical measures. In said device for position detection of the presentinvention, the determination of contact points of depressed intersectingregions by the controller may include: sequentially selecting one andthe other of each pair of the conductive stripes as a driven conductivestripe and a detected conductive stripe, respectively; detecting thepotential of the detected conductive stripe as a positional potentialwhen providing the high and low potentials to both ends of the drivenconductive stripe; electrically coupling an extension resistor and thedriven conductive stripe to form an extension conductive stripe; whenthe extension conductive stripe is not depressed, providing high and lowpotential to the extension conductive stripe to detect the potentialbetween the extension resistor and the driven conductive stripe as anon-depressed potential; when the extension conductive stripe isdepressed, providing high and low potential to the extension conductivestripe to detect the potential between the extension resistor and thedriven conductive stripe as a depressed potential; and determining theposition of a contact point on the driven conductive stripe based on thepositional potential, the non-depressed and depressed potentials of thedriven conductive stripe.

When a depression across conductive stripes is closer to the lowerpotential,

${{Vc} = {\left( {{Vp} - {VL}} \right) - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}}},$

that is, when the potential difference between the high and lowpotentials is known, based on the non-depressed potential Vu, thedepressed potential Vd, the detected potential Vp, the error in thedetected potential Vp can be corrected to create the correct detectedpotential Vc.

When a depression across conductive stripes is closer to the higherpotential,

${{Vc} = {\left( {{Vp} - {VL}} \right) - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}}},$

that is, when the potential difference between the high and lowpotentials is known, based on the non-depressed potential Vu, thedepressed potential Vd, the detected potential Vp, the error in thedetected potential Vp can be corrected to create the correct detectedpotential Vc.

Therefore, the proportion of positional error on the conductive stripehaving contact impedance that crosses intersecting regions can bedetermined based on the change in potential on a position (e.g. a firstor second end) on a conductive stripe.

A sixth objective of the present invention is to provide a method anddevice for detection position misjudgment. In said device for positiondetection of the present invention, in a situation where threedepressions are at three respective vertices of a square region, thedetection of depressed intersecting regions may misjudge a fourth vertexas a depressed intersecting region. The present invention may omit oreliminate misjudgment by comparing the positions of contact points ordepressed intersecting regions, and may further omit or eliminate thecontact point of a misjudged intersecting region.

The objectives of the present invention can be achieved by the followingtechnical measures. In said device for position detection of the presentinvention, the controller determines the depressions to be eliminatedamong all depressions. At least one contact point of all contact pointscorresponding to a depression to be eliminated will fall outside atolerance range of a corresponding intersecting region.

Said controller further includes determining depressions to beeliminated among all depressions, wherein the depressions to beeliminated will need to meet at least one of the following conditions:the total contact impedance is smaller than a threshold value; and theposition of at least one contact point in all contact pointscorresponding to the same depression falls outside the tolerance rangeof a corresponding intersecting region; and determining everynon-eliminated depression positions among all the depressions, whereinthe position of each depression is determined based on the position ofthe contact point of the depressed intersecting region corresponding tothe same depression.

The determination of whether at least one contact point of all contactpoints corresponding to a depression to be eliminated falls outside atolerance range of a corresponding intersecting region is performedbefore the correction of errors in contact points.

A seventh objective of the present invention is to provide a method anddevice for omitting palms using multiple position detection. The presentinvention defines an omitted area on a second type of contact/depressiondetection using a first type of contact/depression detection, whereinthe omitted area may include a plurality of independent omitted areas.The first type of detection is used to define depressions made by a palmor depressions with large areas, i.e. areas to be omitted, so when usingthe second type of position detection, depressions or contacts in theomitted area can be ignored. The first type of detection is a morecoarse way of detecting multiple depressions or contacts, and the secondtype of detection more accurately detects depressions or contactsoutside the omitted area, therefore having the advantages of fastdetection and high accuracy at the same time.

The first and second types of detection can be realized by the samesensors. For example, the first and second conductive stripes can bespaced apart by a piezoelectric layer, and detecting charge couplingbetween the first and second conductive stripes can be the first type ofdetection, while detecting depressed intersecting regions and contactpoints as described before can be the second type of detection.

The objectives of the present invention can be achieved by the followingtechnical measures. Based on the device for correcting position error ofthe present invention, the device comprises: a sensor including aplurality of conductive stripes constituting a plurality of intersectingregions, wherein a pair of depressed conductive stripes intersected inan intersecting region form a contact point due to electrical contact soas to define a depressed intersecting region; a driver for providing ahigh potential and a low potential; a detector for detecting a signal ofat least one conductive stripe; a selector for operatively coupling theconductive stripes with the driver and the detector; and a controllerfor controlling the driver, the detector and the selector to perform atleast the following operations: detectring a non-depressed potential atone end of each conductive stripe; detectring a depressed potential atthe end of each conductive stripe; and determining a proportion of errorat the contact point on each depressed conductive stripe based on thenon-depressed potential and the depressed potential.

The objectives of the present invention can also be achieved by thefollowing technical measures.

The detection of the non-depressed potential and the depressed potentialcomprises: sequentially selecting one of the conductive stripes as adriven conductive stripe; electrically coupling an extension resistorand the driven conductive stripe to form an extension conductive stripe;providing high and low potentials to the extension conductive stripe todetect the potential between the extension resistor and the drivenconductive stripe as the non-depressed potential when the extensionconductive stripe is not depressed; and providing high and low potentialto the extension conductive stripe to detect the potential between theextension resistor and the driven conductive stripe as the depressedpotential when the extension conductive stripe is depressed.

The proportion of error is

$\frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)},$

wherein VH, VL, Vd and Vu are respectively the high potential, the lowpotential, the depressed potential and the non-depressed potential.

The controller further controls the driver, the detector and theselector to perform at least the following operations: detecting theposition of each contact point, wherein when a contact impedance acrossconductive stripes on the same layer is detected at the depressedconductive stripes, the position is the non-corrected position includingan error due to the contact impedance across conductive stripes on thesame layer; and correcting the error according to the non-correctedposition and the proportion of error.

The detection of position of the contact point comprises: sequentiallyselecting one and the other of each pair of the conductive stripes as adriven conductive stripe and a detected conductive stripe, respectively;detecting the potential of the detected conductive stripe as a detectedpotential when providing high and low potentials to both ends of thedriven conductive stripe; and determining the position based on thedetected potentials of the pair of depressed conductive stripes.

The detection of position of the contact point comprises: electricallycoupling an extension resistor and the driven conductive stripe to forman extension conductive stripe; providing high and low potentials toboth ends of the extension conductive stripe to detect the potentialbetween the extension resistor and the driven conductive stripe as thenon-depressed potential when the extension conductive stripe is notdepressed; and providing high and low potentials to the extensionconductive stripe to detect the potential between the extension resistorand the driven conductive stripe as the depressed potential when theextension conductive stripe is depressed.

When the contact point on one of the pair of conductive stripes islocated between the contact impedance across conductive stripes on thesame layer and the end being provided the high potential, the detectedpotential at the position on one of the pair of conductive stripes is

${Vp} - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$

after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively.

When the contact point on one of the pair of conductive stripes islocated between the contact impedance across conductive stripe on thesame layer and the end being provided the low potential, the detectedpotential at the position on one of the pair of conductive stripes is

${Vp} - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$

after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively.

The controller further controls the driver, the detector and theselector to perform the following operation of determining the pair ofthe depressed conductive stripes by determining whether there is aconducting path between the conductive stripes in each intersectingregion, wherein the detection of the non-depressed potential isperformed before the determination of the depressed conductive stripe.

The controller further controls the driver, the detector and theselector to perform the following operation of determining the depressedconductive stripes by determining whether there is a conducting pathbetween each conductive stripe and any intersecting conductive stripe,wherein the conductive stripes are respectively located at a first and asecond conductive stripe layers being intersected, and a plurality ofinsulating spacers are dispersed between the first and the secondconductive stripe layers.

The objectives of the present invention can be achieved by the followingtechnical measures. Based on the method for correcting position error ofthe present invention, the method comprises: providing a plurality ofintersecting regions constituted by a plurality of intersectingconductive stripes, wherein a pair of depressed conductive stripesintersected in an intersecting region form a contact point due toelectrical contact so as to define a depressed intersecting region;detectring a non-depressed potential at one end of each conductivestripe when the conductive stripe is not depressed; etectring adepressed potential at the end of each depressed conductive stripe; anddetermining a proportion of error at the contact point on each depressedconductive stripe based on the non-depressed potential and the depressedpotential.

The objectives of the present invention can also be achieved by thefollowing technical measures.

The detection of the non-depressed potential and the depressed potentialcomprises: sequentially selecting one of the conductive stripes as adriven conductive stripe; electrically coupling an extension resistorand the driven conductive stripe to form an extension conductive stripe;providing high and low potentials to the extension conductive stripe todetect the potential between the extension resistor and the drivenconductive stripe as the non-depressed potential when the extensionconductive stripe is not depressed; and providing high and low potentialto the extension conductive stripe to detect the potential between theextension resistor and the driven conductive stripe as the depressedpotential when the extension conductive stripe is depressed.

The proportion of error is

$\frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)},$

wherein VH, VL, Vd and Vu are respectively the high potential, the lowpotential, the depressed potential and the non-depressed potential.

The method for correcting position error further comprises: detectingthe position of each contact point, wherein when a contact impedanceacross conductive stripes on the same layer is detected at the depressedconductive stripes, the position is the non-corrected position includingan error due to the contact impedance across conductive stripes on thesame layer; and correcting the error according to the non-correctedposition and the proportion of error.

The detection of position of the contact point comprises: sequentiallyselecting one and the other of each pair of the conductive stripes as adriven conductive stripe and a detected conductive stripe, respectively;detecting the potential of the detected conductive stripe as a detectedpotential when providing high and low potentials to both ends of thedriven conductive stripe; and determining the position based on thedetected potentials of the pair of depressed conductive stripes.

The detection of position of the contact point comprises: electricallycoupling an extension resistor and the driven conductive stripe to forman extension conductive stripe; providing high and low potentials toboth ends of the extension conductive stripe to detect the potentialbetween the extension resistor and the driven conductive stripe as thenon-depressed potential when the extension conductive stripe is notdepressed; and providing high and low potentials to the extensionconductive stripe to detect the potential between the extension resistorand the driven conductive stripe as the depressed potential when theextension conductive stripe is depressed.

When the contact point on one of the pair of conductive stripes islocated between the contact impedance across conductive stripes on thesame layer and the end being provided the high potential, the detectedpotential at the position on one of the pair of conductive stripes is

${Vp} - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$

after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively.

When the contact point on one of the pair of conductive stripes islocated between the contact impedance across conductive stripe on thesame layer and the end being provided the low potential, the detectedpotential at the position on one of the pair of conductive stripes is

${Vp} - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$

after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively.

The method for correcting position error further comprises the followingoperation of determining the pair of the depressed conductive stripes bydetermining whether there is a conducting path between the conductivestripes in each intersecting region, wherein the detection of thenon-depressed potential is performed before the determination of thedepressed conductive stripe.

The method for correcting position error further comprises the followingoperation of determining the depressed conductive stripes by determiningwhether there is a conducting path between each conductive stripe andany intersecting conductive stripe, wherein the conductive stripes arerespectively located at a first and a second conductive stripe layersbeing intersected, and a plurality of insulating spacers are dispersedbetween the first and the second conductive stripe layers.

The objectives of the present invention can be achieved by the followingtechnical measures. Based on the method for correcting position errorduring handwriting of the present invention, the method comprises:providing a plurality of intersecting regions constituted by a pluralityof intersecting conductive stripes; determining a depression of a penand a depression of a palm across conductive stripes on the intersectingregions; determining the position of the depression of the pen, whereinon the conductive stripe which is depressed simultaneously by the penand the palm, an error in the position of the depression of the pen iscaused by the depression of the palm across conductive stripes; andcorrecting the error when the pen depresses the conductive stripedepressed by the palm.

The objectives of the present invention can also be achieved by thefollowing technical measures.

A pair of depressed conductive stripes intersected in an intersectingregion form a contact point due to electrical contact so as to define adepressed intersecting region, and the position of the depression of thepen is determined based on the position of at least one contact point,wherein the determination of the position of the contact pointcomprises: sequentially selecting one and the other of the pair ofdepressed conductive stripes as a driven conductive stripe and adetected conductive stripe, respectively; detecting the potential of thedetected conductive stripe as a detected potential when providing a highand a low potentials to both ends of the driven conductive stripe; anddetermining the position of the contact point based on the detectedpotentials of the pair of depressed conductive stripes.

The correction of the error comprises: detecting a non-depressedpotential at one end of the conductive stripe before the palm depressesthe conductive stripe; detecting a depressed potential at the end of theconductive stripe after the palm depresses the conductive stripe; andcorrecting the error based on the non-depressed potential, depressedpotential and the position of the contact point detected on theconductive stripe depressed by the palm.

The error is corrected based on a proportion of error, and thedetermination of the proportion of error comprises: detecting anon-depressed potential at one end of each conductive stripe; detectinga depressed potential at the end of each depressed conductive stripe;and determining the proportion of error on each depressed conductivestripe based on the non-depressed potential and depressed potential.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thefollowing detailed description of the preferred embodiments, withreference made to the accompanying drawings, wherein:

FIG. 1 is a schematic diagram depicting a prior-art device for positiondetection;

FIG. 2A is a schematic diagram depicting the structure of a device forposition detection of the present invention;

FIG. 2B is a flowchart illustrating a method for position detection ofthe present invention;

FIG. 3 is a flowchart illustrating driving and detecting of depressedintersecting regions of the present invention;

FIGS. 4A, 4B, and 4C are schematic diagrams depicting the structure of adevice for position detection of the present invention detectingdepressed intersecting regions;

FIG. 5 is a flowchart illustrating a method for detecting contact pointsof the present invention;

FIGS. 6A, 6B, and 6C are schematic diagrams depicting the structure of adevice for position detection of the present invention detecting contactpoints;

FIG. 7 is a flowchart illustrating a method for detecting depressedconductive stripes of the present invention;

FIGS. 8A, 8B, and 8C are schematic diagrams depicting the structure of adevice for position detection of the present invention detectingdepressed conductive stripes;

FIG. 9 is a schematic diagram depicting an image of an intersectingregion depressed by the end of a pen;

FIGS. 10A and 10B are schematic diagrams depicting an image ofintersecting regions depressed by one and two fingers;

FIGS. 11A and 11B are schematic diagrams depicting the structure of adevice for detecting compact impedance of the present invention;

FIG. 11C is a schematic diagrams depicting the structure of anotherdevice for detecting compact impedance of the present invention;

FIGS. 12A and 12B are schematic diagrams depicting the situations ofwriting with a pen or finger of the present invention;

FIG. 12C is a schematic diagram depicting a finger depression;

FIG. 13 is a schematic diagram depicting the structure of another devicefor position detection of the present invention;

FIG. 14 is a schematic diagram depicting a misjudged depressedintersecting region;

FIG. 15A is a schematic diagram depicting the detection of the positionof a pen depression;

FIG. 15B is a schematic diagram depicting a positional error caused bycontact impedance across intersecting regions;

FIGS. 16A, 17A, 17B, 17C, and 17D are schematic diagrams depicting thestructures for correcting positional errors caused by contact impedanceacross intersecting regions of the present invention; and

FIG. 16B is a flowchart illustrating the steps for correcting positionalerrors caused by contact impedance across intersecting regions of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure can be described by the embodiments given below.It is understood, however, that the embodiments below are notnecessarily limitations to the present disclosure, but are used to atypical implementation of the invention.

Having summarized various aspects of the present invention, referencewill now be made in detail to the description of the invention asillustrated in the drawings. While the invention will be described inconnection with these drawings, there is no intent to limit it to theembodiment or embodiments disclosed therein. On the contrary the intentis to cover all alternatives, modifications and equivalents includedwithin the spirit and scope of the invention as defined by the appendedclaims.

It is noted that the drawings presents herein have been provided toillustrate certain features and aspects of embodiments of the invention.It will be appreciated from the description provided herein that avariety of alternative embodiments and implementations may be realized,consistent with the scope and spirit of the present invention.

It is also noted that the drawings presents herein are not consistentwith the same scale. Some scales of some components are not proportionalto the scales of other components in order to provide comprehensivedescriptions and emphasizes to this present invention.

The present invention is described by the following specificembodiments. Those with ordinary skills in the arts can readilyunderstand the other advantages and functions of the present inventionafter reading the disclosure of this specification. In order to provideclear illustration and understanding, some parts of the diagrams may notbe drawn to scale, some are exaggerated with respect to others, and someare omitted.

Referring to FIG. 2A, the present invention provides a device forposition detection 20, which includes a sensor 21, a selector 22, adriver 23, a detector 24, a controller 25 and a host 26.

Referring to FIG. 2B, the present invention provides a method forposition detection. First, as shown in step 210, at least one depressedintersecting region on the device for position detection 20 is detected.Next, as shown in step 220, at least one contact point is detected basedon each depressed intersecting region.

The sensor 21 includes a plurality of conductive stripes 212. Thesestripes include a plurality of first and second stripes intersecting ona plurality of intersecting regions 214. When an object depresses thedevice 20, some of the first and second stripes contact one another toform at least one contact point corresponding to the depression made bythe object, wherein the conductive stripes intersecting an intersectingregion are a pair of depressed conductive stripes.

The first and second stripes do not contact each other while not beingdepressed. In one example of the present invention, a plurality ofinsulating spacers are dispersed between the first and second stripes toseparate them. In addition, the present invention does not limit thepositions of the first and second conductive stripes, the first stripescan be on top or the second stripes on top. In one example of thepresent invention, the first and second stripes are arranged indifferent axes, so that the plurality of intersecting regionsconstitutes an intersecting matrix. For example, the first conductivestripes are arranged in the horizontal direction, and the secondconductive stripes are arranged in the vertical direction, or viceversa. The first and second conductive stripes are disposed at differentlayers.

The first and second stripes can each have predetermined widths, thusintersecting regions are formed at intersections of the first and secondstripes. It should be apparent to those skilled in the art that thewidths of each stripe can be different, so the intersecting regions canalso be different. The present invention is not limited thereto.

In addition, it should be apparent to those skilled in the art that,based on different objects, the number and area of the intersectingregions in which the first and second stripes contact each other can bedifferent. In a preferred example of the present invention, the contactpoint on each intersecting region is singular, that is, no matter whatthe size of the depressed area on an intersecting region is, thedepressed area on this intersecting region is regarded as a singlecontact point. It should be apparent to those skilled in the art thatwhen the intersecting region is larger, there can be two or more contactpoints. In this circumstance, two different contact points can beidentified based on the order of depression in time. The number of thecontact points in a single intersecting region in the present inventionincludes but is not limited to one.

Controller 25 electrically couples with and controls selector 22, driver23, and detector 24. Selector 22 operatively couples driver 23 anddetector 24 to sensor 21 based on instructions from controller 25. In anexample of the present invention, driver 23 and detector 24 operativelycouple with sensor 21 via selector 22 based on instructions fromcontroller 25. For example, selector 22 selects one or two ends of atleast one conductive stripe based on instructions from controller 25,and uses the selected one or two ends of the stripe as coupling ends toelectrically couple one or both of driver 23 and detector 24.

In an example of the present invention, the coupling end is directlycoupled to driver 23 or detector 24 via selector 22. In another exampleof the present invention, the coupling end is indirectly coupled todriver 23 or detector 24 via selector 22 in combination with anextension resistor. For example, the extension resistor electricallycouples with the selected conductive stripe to form an extension stripe,and the extension resistor electrically couples with driver 23 anddetector 24, that is, the coupling end electrically couples with driver23 and detector 24 via the extension resistor.

In an example of the present invention, driver 23 provides a highpotential and a low potential at two coupling ends. The high and/or lowpotentials can be provided to two coupling ends directly or indirectlyvia an extension resistor. The two coupling ends can be on the same ordifferent conductive stripes. For example, a first end of a firstconductive stripe and a second end of a second conductive stripe.

In another example of the present invention, detector 24 detects signalsat the coupling ends. The detected signals can be potential, current,capacitance, charge transfer or other electrical signals. A coupling endoperatively coupled by detector 24 can be abovementioned first end or asecond end corresponding to the first end on the conductive stripe. Forexample, the first end can be the coupling end of the conductive stripecoupled to the extension resistor.

Accordingly, control of selector 22, driver 23, and detector 24 bycontroller 25 includes but is not limited to: directly or indirectly viaan extension resistor providing high and low potentials to first andsecond ends of the same conductive stripe, respectively; directly orindirectly via an extension resistor providing high and low potentialsto a first end of at least one first stripe and a second end of at leastone second stripe, respectively; detecting a signal between the stripeand the extension resistor; when one of a pair of depressed stripesbeing provided with high and low potentials, detecting potentials at oneor two ends of another one of the pair of depressed stripes; anddetecting potentials at the second ends of one of those first stripesand one of those second stripes, respectively.

In an example of the present invention, controller 25 can be integratedinto host 26, including but not limited to a processor, co-processor,digital signal processor (DSP) or other programmable circuits of host26. In another example of the present invention, controller 25 is notpart of host 26.

Controller 25 determines each depression based on signals detected bydetector 24, wherein an object may cause one or more depressions, forexample, when a palm depresses, it may cause an area or severalindependent depressions. In addition, controller 25 may ignore (oreliminate or filter) some depressions based on the signals detected bydetector 24. For example, ignoring palm depression during handwriting,or ignoring non-existing depressions caused by misjudgment.Additionally, controller 25 further provides locations of depressions tohost 26.

The present invention further includes tracking of depressionssubsequent to each depression and determining at least one gesture basedon each depression and its subsequent depressions, and determining acommand corresponding to the gesture. The gesture can be determined bycontroller 25 or host 26. When controller 25 is not integrated as partof host 26, controller 25 can provide the locations of the depressionsand host 26 can perform said depression omission and gesturedetermination. Alternatively, controller 25 can perform said depressionomission and then provide the locations of the depressions to host 26for gesture determination. Alternatively, controller 25 can perform saiddepression omission and gesture determination, and provide one or bothof depression locations or gestures. When controller 25 is integratedinto host 26, depression omission and gesture determination can beprocessed by controller 25 or host 26.

FIG. 3 illustrates a method for detecting depressed intersecting regionsaccording to the present invention. As shown in step 310, high and lowpotentials are respectively provided to first and second conductivestripes intersected in each intersecting region, and as shown in step320, each depressed intersecting region is determined by determiningwhether there is a conducting path between the first and secondconductive stripes in each intersecting region.

For example, a high potential is sequentially provided to the firstconductive stripes. When each first conductive stripe is at highpotential, a low potential is sequentially provided to each of thesecond conductive stripes. In this way, each of the intersecting regionson the first conductive stripe being driven can be sequentiallydetermined to see if it is depressed.

Accordingly, in a preferred embodiment of the present invention, adevice for position detection detecting depressed intersecting regionsis shown in FIG. 4A, which includes a detecting unit V1 and a drivingunit D1. The detecting unit provides high potential VH1 and lowpotential VL1, wherein high potential VH1 is provided to one of firstconductive stripes (X1, X2, . . . , X8), whereas low potential VL1 isprovided to one of second conductive stripes (Y1, Y2, . . . , Y8). Thedetecting unit V1 detects conductive stripes provided with highpotential VH1. The numbers of the first stripes (X1, X2, . . . , X8) andsecond stripes (Y1, Y2, . . . , Y8) are given for illustration purposeonly, the present invention is not limited to these.

The detection of the first conductive stripes provided with highpotential VH1 includes but is not limited to detection of potential,current or logic level, and the detection can be done at one or bothends of the first conductive stripes provided with high potential VH1.For example, in an example of the present invention, high potential VH1can be provided to one of the first stripes (X1, X2, . . . , X8) via anextension resistor Re, and depressed intersecting regions can bedetermined by detecting the potential, current or logic level at one endof the extension resistor Re (between the extension resistor Re and theconductive stripe).

For example, when high potential VH1 and low potential VL1 are providedto conductive stripes X1 and Y1, respectively, the detecting unit V1 candetermine if an intersecting region intersected by stripes X1 and Y1 isdepressed. For example, when detecting the intersecting regionintersected by stripes X1 and Y1, the driving unit D1 provides highpotential VH1 and low potential VL1 to conductive stripes X1 and Y1,respectively, and if the intersecting region intersected by stripes X1and Y1 is not depressed as shown in FIG. 4B, current will not flow fromstripe X1 to stripe Y1, thus no significant change in the signal of theextension resistor Re is observed, and the detecting unit V1 may thendetermine that the intersecting region intersected by stripes X1 and Y1is not depressed. Similarly, when detecting the intersecting regionintersected by stripes X8 and Y7, the driving unit D1 provides highpotential VH1 and low potential VL1 to conductive stripes X8 and Y7,respectively, current will flow from stripe X8 to stripe Y7, and thedetecting unit V1 may then determine that the intersecting regionintersected by stripes X8 and Y7 is depressed by detecting a change inthe potential of the extension resistor Re. It should be apparent tothose skilled in the art that low potential VL1 can be provided to oneof the first stripes (X1, X2, . . . , X8) and high potential VH1 can beprovided to one of the second stripes (Y1, Y2, . . . , Y8), as shown inFIG. 4C. Said driving unit D1 and detecting unit V1 include but are notlimited to being integrated in said driver 23 and detector 24,respectively, and the driving of driving unit D1 and detection ofdetecting unit V1 include but are not limited to control by controller25. Control of selector 22, driver 23, and detector 24 by controller 25includes but is not limited to: indirectly providing high and lowpotentials to a first end of at least one first conductive stripe and afirst end of at least one second conductive stripe; and detecting thesignal between the stripe and the extension resistor.

FIG. 5 is a flowchart depicting steps for detecting at least one contactpoint based on each depressed intersecting region. As shown in step 510,each of conductive stripes intersecting each depressed intersectingregion is respectively driven, the two ends of the driven stripe areprovided with a high potential and a low potential, respectively. Asshown in step 520, when one of a pair of conductive stripes in adepressed intersecting region is driven, the other stripe not driven isdetected so as to determine the location of each contact point. For thedetection of the stripe not driven, one or both ends of the stripe notdriven can be detected simultaneously.

In other words, in each depressed intersecting region, one of a pair ofconductive stripes in the depressed intersecting region is driven, andthe other stripe in the pair not driven is detected to determine thetwo-dimensional coordinates for a contact point. For example, the firstconductive stripe in the pair of stripes is first driven and the secondconductive stripe is detected to detect the location of the contactpoint on the axis of the first conductive stripe as a first coordinatePx in the two-dimensional coordinates. Then, the second conductivestripe in this pair of stripes is driven and the first conductive stripeis detected to detect the location of the contact point on the axis ofthe second conductive stripe as a second coordinate Py in thetwo-dimensional coordinates. The order of driving the first and secondconductive stripes is not limited to this. After both first and secondconductive stripes are detected, the position of the contact point onthe axes of the first and second conductive stripes can be determined.This position can be indicated by the two-dimensional coordinates (Px,Py).

In a preferred example of the present invention, a device for positiondetection 20 detecting contact points is shown in FIG. 6A. The devicefor position detection includes a plurality of conductive stripes, adetecting unit V2 and a driving unit D2. The plurality of conductivestripes are said first conductive stripes (X1, X2, . . . , X8) andsecond conductive stripes (Y1, Y2, . . . , Y8). The driving unitprovides high potential VH2 and low potential VL2 to drive one of theconductive stripes, and detecting unit V2 detects one of conductivestripes intersecting the driven stripe. Thus, when a driven stripeintersects a detected stripe in a depressed intersecting region,detecting unit V2 can determine the position of a contact point P on thedriven conductive stripe.

For example, when a depressed intersecting region is an intersectingregion between conductive stripes X8 and Y7 as shown in FIG. 6B, thedriving unit first provides high potential VH2 and low potential VL2 toboth ends of stripe X8, and detects stripe Y7 to determine the locationPx of the contact point P on stripe X8 (axis of the first conductivestripe). Similarly, as shown in FIG. 6C, the driving unit then provideshigh potential VH2 and low potential VL2 to both ends of stripe Y7, anddetects stripe X8 to determine the location Py of the contact point P onstripe Y7 (axis of the second conductive stripe). Driving unit D2 anddetecting unit V2 include but are not limited to being integrated intosaid driver 23 and detector 24, respectively, and the driving of drivingunit D1 and detection of detecting unit V1 include but are not limitedto control by controller 25. Control of selector 22, driver 23, anddetector 24 by controller 25 includes but is not limited to: directly orindirectly via an extension resistor providing high and low potentialsto first and second ends of the same conductive stripe; and when one ofa pair of depressed conductive stripes is provided with high and lowpotentials, potential at one or both ends of the other one in the pairare detected.

In an example of the present invention, driving unit D2 and detectingunit V2 sequentially detects each intersecting region to detect alldepressed intersecting regions, and driving unit D2 and detecting unitV2 sequentially detects each intersecting region to determine a 2-Dimage of the first conductive stripe axis and a 2-D image of the secondconductive stripe axis in each intersecting region, and then determinesthe position of each contact point based on the 2-D images of the firstand second conductive stripe axes in each depressed intersecting region.Obviously, compared to selecting depressed intersecting regions and thendetermining the position of each contact point for the depressedintersecting regions mentioned above, this example is less efficient.

In the above description, the detection of detecting unit V1 includesbut is not limited to detection of potential, current or logic level,whereas the detection of detecting unit V2 is the actual value ofsignals, such as voltage value or current value, and each intersectingregion requires detection in two dimensions, thus the detection ofdepressed intersecting regions is much quicker than the detection ofcontact points.

The numbers of the first stripes (X1, X2, . . . , X8) and second stripes(Y1, Y2, . . . , Y8) are given for illustration purpose only, thepresent invention is not limited to these, and they can be modifiedaccording to design needs. Thus, when the numbers of the first andsecond conductive stripes are m and n, respectively, there will be m*nintersecting regions to be detected. The more the number of the firstand second conductive stripes, the longer the detection will take. Thus,the) speed of detecting all intersecting regions has to be increased toenhance the overall performance.

Accordingly, an example of the present invention is shown in FIG. 7. Asshown in step 710, a plurality of depressed conductive stripes on adevice for position detection is detected. Then, as shown in step 720,potentially depressed intersecting regions on which depressed conductivestripes intersect are determined based on the depressed conductivestripes. Then, as shown in step 730, at least one depressed intersectingregion on the device for position detection is detected based on thepotentially depressed intersecting regions. Further, as shown in step740, at least one contact point is determined based on each depressedintersecting region.

In other words, it is first determined which first and second conductivestripes are depressed, and potential depressed intersecting regions aredetermined based on the those depressed first and second conductivestripes. Compared to FIGS. 3, 4A, and 4C which detect depressedintersecting regions out of all intersecting regions, the presentexample detects depressed intersecting regions out of potentiallydepressed intersecting regions.

In a preferred example of the present invention, a device for positiondetection detecting depressed conductive stripes is shown in FIG. 8A.The device for position detection includes a plurality of conductivestripes, detecting unit V3 and driving unit D3. The conductive stripesare said first conductive stripes (X1, X2, . . . , X8) and secondconductive stripes (Y1, Y2, . . . , Y8). Driving unit D3 provides highpotential VH3 to one of these conductive stripes, and provides lowpotential VL3 to all the conductive stripes intersecting with theconductive stripe provided with high potential VH3 to respectivelydetect depressed conductive stripes.

For example, as shown in FIG. 8B, driving unit D3 provides highpotential VH3 to one of the first conductive stripes (X1, X2, . . . ,X8), and provides low potential VL3 to all the second conductive stripes(Y1, Y2, . . . , Y8) intersecting with the conductive stripe providedwith high potential VH3. Detecting unit V3 detects first detectingstripe provided with high potential VH3. For example, first conductivestripes X1, X2, . . . , or X7 are not depressed, so current does notflow from detected first conductive stripes X1, X2, . . . , or X7 to anysecond conductive stripe, so detecting unit V3 does not detect thatfirst conductive stripes X1, X2, . . . , or X7 are depressed. When firstconductive stripe X8 is provided with high potential VH3, current flowfrom first conductive stripe X8 to second conductive stripe Y7, sodetecting unit V3 detects that first conductive stripe X8 is depressed.

Similarly, driving unit D3 provides high potential VH3 to one of thesecond conductive stripes (Y1, Y2, . . . , Y8), and provides lowpotential VL3 to all the first conductive stripes (X1, X2, . . . , X8)intersecting with the second conductive stripe provided with highpotential VH3. Detecting unit V3 thereby detects depressed a secondconductive stripe, such as second conductive stripe Y7.

The detection of the conductive stripes provided with high potential VH3is similar to said detection of the first conductive stripes providedwith high potential VH1, including but not limited to detection ofpotential, current or logic level, and the detection can be done at oneor both ends of the first conductive stripes provided with highpotential VH3. For example, in an example of the present invention, highpotential VH3 can be provided to one of the stripes via an extensionresistor Re, and depressed conductive stripes can be determined bydetecting the potential, current or logic level at one end of theextension resistor Re (between the extension resistor Re and theconductive stripe).

Thus, at least one potential depressed intersecting region in whichdepressed conductive stripes intersect can be determined by thedepressed conductive stripes (e.g. conductive stripes X8 and Y7). Whenthe number of potential depressed intersecting regions is not more thanthree, the potential depressed intersecting regions are the depressedintersecting regions.

In addition, driving unit D3 can simultaneously provide high potentialVH3 to a plurality of conductive stripes, and detecting unit V3 cansimultaneously detect some or all conductive stripes provided with highpotential VH3, however, the conductive stripes provided with highpotential VH3 all have to be first conductive stripes or secondconductive stripes.

The conductive stripes are selectively chosen to be driven or detected.It should be apparent to those skilled in the art that theimplementation of selection of the conductive stripes may include butnot limited to a switching device such as a switch, a multiplexer or abus; the present invention does not limited to these. In addition, saidhigh potentials VH1, VH2, and VH3 can be the same or different;similarly, said low potentials VL1, VL2, and VL3 can be the same ordifferent; the present invention does not limited to these. Moreover,said extension resistor can be the same or different; the presentinvention does not limited to these.

Said driving unit D3 and detecting unit V3 include but are not limitedto being integrated in said driver 23 and detector 24, respectively, andthe driving of driving unit D1 and detection of detecting unit V1include but are not limited to control by controller 25. Control ofselector 22, driver 23, and detector 24 by controller 25 includes but isnot limited to: indirectly providing high and low potentials to a firstend of at least one first conductive stripe and a first end of at leastone second conductive stripe; and detecting the signal between thestripe and the extension resistor.

According to the above, all contact points after detection may exhibitan image of intersecting region as shown in FIG. 9. If an object has asharp end, the depression of this object will produce a correspondingsignal of contact point on the image of intersecting region. When afinger or an object with a blunt end depresses, the image ofintersecting region may exhibit several corresponding signals of contactpoints, as shown in FIG. 10A.

Contact points corresponding to the same object will gather together, asshown in FIG. 10B, thus contact points corresponding to each depressingobject can be analyzed and identified. In an example of the presentinvention, the time each contact point is generated can be used toanalyze contact points corresponding to each depressing object.

By analysis of the image of intersecting regions, the shape of theobject can be determined by the number of contact points for thedepressing object. For example, it can be determined whether the objectis a pen or a finger based on how many contact points there arecorresponding to the object. In addition, the pressure exerted by adepressing object can be simulated based on the number of contact pointsfor the depressing object.

Moreover, based on difference comparisons of the images of intersectingregions at consecutive time points, trajectory of a moving object can beoutlined for determining a gesture. For example, a gesture can bedetermined by trajectories made by a pair of depressing objects. Thetrajectories of the objects may include: moving away from each other,one moving away from the other, moving towards each other, one movingtowards the other, rotating around each other, and one rotating aroundthe other.

In an example of the present invention, it can be determined whether anobject is a pen or a finger based on how many contact points there arecorresponding to the object. In addition, the pressure exerted by adepressing object can be simulated based on the number or spreadingrange of contact points for the depressing object. When there are morethan one contact points corresponding to an object, the center of massof the contact points corresponding to the object can be regarded as thedepression location of the object.

Accordingly, an example of the present invention is a device forposition detection, which includes a plurality of conductive stripes, afirst and a second driving unit, and a first and a second detectingunit. The conductive stripes include a plurality of first and secondconductive stripes intersecting each other to form a plurality ofintersecting regions. When at least one object depresses the device, thefirst and second conductive stripes contact each other to form at leastone contact point corresponding to the depressing object.

The first driving unit and the first detecting unit can be driving unitD1 and detecting unit V1 described in steps 310 and 320 in FIG. 3 andFIGS. 4A to 4C. When the first driving unit respectively provides a highpotential and a low potential to a first and a second conductive stripeintersecting each intersecting region, the second detecting unit detectsthe first conductive stripe provided with the high potential to detecteach depressed intersecting region.

The second driving unit and the second detecting unit can be drivingunit D2 and detecting unit V2 described in steps 510 and 520 in FIG. 5and FIGS. 6A to 6C. The second driving unit respectively drives eachconductive stripe intersecting in each depressed intersecting region.When one of a pair of conductive stripes intersecting in a depressedintersecting region is driven by the second driving unit, the seconddetecting unit detects the other conductive stripe in the pair notdriven by the second driving unit to detect the position of each contactpoint, wherein the second driving unit provides high and low potentialsto the driven conductive stripe.

Relevant details of the present example have been disclosed previouslyand will not be repeated herein.

In addition, another example of the present invention is a device forposition detection, which includes a plurality of conductive stripes, afirst, a second, and a third driving unit, and a first, a second, and athird detecting unit. The conductive stripes include a plurality offirst and second conductive stripes intersecting each other to form aplurality of intersecting regions. When at least one object depressesthe device, the first and second conductive stripes contact each otherto form at least one contact point corresponding to the depressingobject.

The first driving unit and the first detecting unit can be driving unitD3 and detecting unit V3 described in steps 710 to 740 in FIG. 7 andFIGS. 8A to 8C. The first driving unit selectively provides a highpotential to conductive stripes, and the first detecting unit detectsthe conductive stripes provided with the high potential by the firstdriving unit, so as to detect a plurality of depressed conductivestripes. Each intersecting region in which the depressed conductivestripes intersect is a potentially depressed intersecting region. Whenthe conductive stripe provided with the high potential by the firstdriving unit is a first conductive stripe, the first driving unitprovides a low potential to all second conductive stripes, and when theconductive stripe provided with the high potential by the first drivingunit is a second conductive stripe, the first driving unit provides alow potential to all first conductive stripes.

The second driving unit and the second detecting unit can be drivingunit D1 and detecting unit V1 described in steps 310 and 320 in FIG. 3and FIGS. 4A to 4C. When the second driving unit respectively andselectively provides high and low potentials to first and secondconductive stripes in each potentially depressed intersecting region,the second detecting unit detects the first conductive stripe providedwith the high potential to detect each depressed intersecting region.

The third driving unit and the third detecting unit can be driving unitD2 and detecting unit V2 described in steps 510 and 520 in FIG. 5 andFIGS. 6A to 6C. The third detecting unit respectively drives theconductive stripes in each depressed intersecting region. When one of apair of conductive stripes in a depressed intersecting region is drivenby the third driving unit, the third detecting unit detects the otherconductive stripe in the pair not driven by the third driving unit, soas to detect the position of each contact point, wherein the thirddriving unit provides high and low potentials to the driven conductivestripe.

Relevant details of the present example have been disclosed previouslyand will not be repeated herein.

Compared to the prior art, the driving and detecting methods of thepresent invention will not cause signals of contact points detected atlater times to become weaker due to too many contact points detectedearlier, so there is no need to provided different determining standardsfor different detection regions. In addition, the present invention notonly detects which regions have been depressed, but also determines theposition of contact points in the intersecting regions, that is, thepresent invention achieves higher resolution with fewer conductivestripes.

In addition, the present invention further includes palm omittingfunction during handwriting. Under the handwriting mode, depressionsmade by the end of a pen and the palm can be distinguished, and thetrajectory of the pen can be traced. Accordingly, an example of thepresent invention is a device for position detection, which includes aplurality of conductive stripes, a first, a second, a third, and afourth driving unit, and a first, a second, and a third detecting unit,and a fourth and a fifth detecting unit. The conductive stripes includea plurality of first and second conductive stripes intersecting eachother to form a plurality of intersecting regions. When at least oneobject depresses the device, the first and second conductive stripescontact each other to form at least one contact point corresponding tothe depressing object. Based on the descriptions above, when at leastone object depresses the device, each depressed intersecting region andcontact points in each depressed intersecting region can be detected.

In an example of the present invention, a method and a device fordetermining contact impedance based on locations of contact points isprovided, wherein the contact impedance of each contact point isdetermined after each contact point is detected. The fourth driving unitand the fourth and fifth detecting units, are respectively driving unitD4 providing high potential VH4 and low potential VL4 and detectingunits V4 and V5 shown in FIG. 11A. The fourth driving unit selectivelyand respectively provides high potential VH4 and low potential VL4 toeach depressed intersecting region, and detecting units V4 and V5respectively detects the potentials of conductive stripes provided withhigh potential VH4 and low potential VL4 at the contact point. Forexample, when high potential VH4 is provided to one end of a firstconductive stripe in a depressed intersecting region, detecting unit V4detects a first potential P1 at the other end of the first conductivestripe, and when low potential VL4 is provided to one end of a secondconductive stripe in the depressed intersecting region, detecting unitV5 detects a second potential P2 at the other end of the secondconductive stripe. Since on conductive stripes where materials areuniformly distributed, the impedance is approximately proportional tothe position. Accordingly, the impedances R1 and R2 can be deduced fromthe position of the contact point on the first and second conductivestripes. According to high potential VH4, low potential VL4, first andsecond potentials P1 and P2 and impedances R1 and R2, impedance Rbetween the two conductive stripes at the contact point can becalculated.

According to an example of the present invention, a process fordetermining contact impedance is provided. This process can be performedby said controller, including but not limited to determining the contactimpedance for each depressed intersecting region. The contact impedanceis determined by the potentials of one and the other of a pair ofconductive stripes in the depressed intersecting region at the contactpoint and the position of the contact point.

The above determination of contact impedance may include: determining afirst dimensional location and a second dimensional location of thecontact point, and determining a first dimensional impedance and asecond dimensional impedance based on the first dimensional location andthe second dimensional location; detecting a first contact potential anda second contact potential of one and the other of a pair of conductivestripes when a high potential and a low potential is provided to one andthe other of a pair of conductive stripes, respectively; determining thecontact impedance based on the first dimensional impedance, the seconddimensional impedance, the high potential, the low potential, the firstcontact potential, and the second contact potential.

Said driving unit D4 and detecting units V4 and V5 include but are notlimited to being integrated in said driver 23 and detector 24,respectively, and the driving of driving unit D4 and detection ofdetecting units V4 and V5 include but are not limited to control bycontroller 25. Control of selector 22, driver 23, and detector 24 bycontroller 25 includes but is not limited to: directly or indirectly viaan extension resistor respectively providing high and low potentials toa first end of at least one first conductive stripe and a first end ofat least one second conductive stripe; and respectively detecting thepotentials at the second ends of one of the first conductive stripes andone of the second conductive stripes.

In another example of the present invention, a method and device fordetermining contact impedances based on locations of intersectingregions is provided. Impedances R1 and R2 can be deduced based on thelocation of the depressed intersecting region, as shown in FIG. 11B. Forexample, impedances R1 and R2 can be deduced based on the number ofintersecting regions between a depressed intersecting region on thefirst and second conductive stripes and the ends with high and lowpotentials. For example, when there are m intersecting regions betweenthe depressed intersecting region and one end provided with highpotential VH4, the impedance R1 is m units, or m+1 units (including thedepressed intersecting region). Similarly, when there are n intersectingregions between the depressed intersecting region and one end providedwith high potential VH4, the impedance R1 is n units or n+1 units. Thus,detection of impedances R1 and R2 can be performed after determining thedepressed intersecting region and before detecting the contact point.

According to an example of the present invention, the method and devicefor determining contact impedance based on locations of intersectingregions includes a process for determining contact impedances. Thisprocess can be performed by said controller, including but not limitedto determining the contact impedance for each depressed intersectingregion. The contact impedance is determined by the potentials of one andthe other of a pair of conductive stripes in the depressed intersectingregion at the contact point and the position of the depressedintersecting region.

The above determination of contact impedance may include: determining afirst dimensional impedance and a second dimensional impedance based onthe location of the depressed intersecting region; detecting a firstcontact potential and a second contact potential of one and the other ofa pair of conductive stripes when a high potential and a low potentialis provided to one and the other of a pair of conductive stripes,respectively; determining the contact impedance based on the firstdimensional impedance, the second dimensional impedance, the highpotential, the low potential, the first contact potential, and thesecond contact potential.

From the above, formula 1 can be derived as:(P1−P2)/(VH4−VL4)=R/(R1+R+R2), and formula 2 can be derived from this asR=(R1+R2)/(((VH4−VL4)/(P1−P2))−1). That is, contact impedance R at thecontact point between the first and second conductive stripes iscalculated from high potential VH4, low potential VL4, first and secondpotentials P1 and P2 (e.g. the first contact potential and the secondcontact potential) and impedances R1 and R2 (e.g. the first dimensionalimpedance and the second dimensional impedance). In other words, thecontact impedance at the contact point between the first and secondconductive stripes can be determined based on the location of thedepressed intersecting region or the location of the contact point,potential differences provided between depressed conductive stripes,potential differences detected at the contact point of the first andsecond conductive stripes.

In addition, as shown in FIGS. 11A and 11B, the above detection of eachdepressed intersecting region can be done based on first potential P1detected by fourth detecting unit V4 and second potential P2 detected byfifth detecting unit V5. For example, when first potential P1 is nothigh potential VH4 or second potential P2 is not low potential VL4, itcan be determined that the intersecting region provided with the highand low potentials is a depressed intersecting region. For example, whenthe potential difference between first potential P1 and second potentialP2 is not the potential difference between the high and low potentials,it can be determined that the intersecting region provided with the highand low potentials is a depressed intersecting region. It should beapparent to those skilled in the art that the determination of whetherfirst potential P1 is high potential VH4 and the determination ofwhether second potential P2 is low potential VL4 are performed within atolerance range.

Thus, as shown in FIG. 11B, when driving unit D4 is used to provide highpotential VH4 and low potential VL4 to each intersecting region,depressed intersecting regions and contact impedances R between thefirst and second conductive stripes in the depressed intersectingregions can be identified. In other words, the detection of depressedintersecting regions can be performed based on one or both of a firstpotential and a second potential (e.g. determine if there is aconduction path between the first and second conductive stripes), andthe contact impedances at the contact points between the first andsecond conductive stripes in the depressed intersecting regions can bedetermined at the same time as the detection of the depressedintersecting regions.

Similar to those shown in FIGS. 3 to 4C and 7 to 8C, the method fordetermining depressed intersecting regions described in FIG. 11A or 11Bcan include first determining depressed conductive stripes, thendetermining potentially depressed intersecting regions based on thedepressed conductive stripes, and then determining depressedintersecting regions based on the potentially depressed intersectingregions. In an example of the present invention, one of high potentialVH4 and low potential VL4 is operatively coupled to a conductive stripe,and the other one of high potential VH4 and low potential VL4 isoperatively coupled to a plurality of conductive stripe to determinedepressed conductive stripes.

For example, high potential VH4 is sequentially and operatively coupledto every first conductive stripe. When any first conductive stripe isoperatively coupled, low potential VL4 is simultaneously coupled to allsecond conductive stripes. The first conductive stripe is determined tobe depressed if there is a conduction path between the first conductivestripe and the second conductive stripe. For example, anoperatively-coupled first conductive stripe is determined to bedepressed if first potential P1 detected by detecting unit V4 is equalto or approximate high potential VH4. Similarly, high potential VH4 iscoupled to all first conductive stripes, and low potential VL4 issequentially and operatively coupled to every second conductive stripe.The second conductive stripe is determined to be depressed if there is aconduction path between the first conductive stripe and the secondconductive stripe. Next, potentially depressed intersecting regions aredetermined based on all the depressed conductive stripes. For example,intersecting regions in which the depressed first conductive stripes andthe depressed second conductive stripes intersected are regarded as thepotentially depressed intersecting regions. Next, each depressedintersecting region is identified based on the determination of saidpotentially depressed intersecting regions, and the contact impedance oneach depressed intersecting region is also determined at the same time.In this example, each depressed intersecting region can be determinedwithout an extension resistor, the contact point and the contactimpedance of each depressed intersecting region can also be determined,wherein the determination of the impedance can be done before thedetermination of the contact point.

Further, in an example of the present invention, a device for positiondetection detecting depressed intersecting regions is shown in FIG. 11C,the device includes detecting units V1, V6, and V7 and a driving unitD1. Driving unit D1 provides high potential VH1 and low potential VL1,wherein high potential VH1 is provided to one of first conductivestripes (X1, X2, . . . , X8), while low potential VL1 is provided to oneof second conductive stripes (Y1, Y2, . . . , Y8). Detecting unit V1detects the conductive stripe that is provided with high potential VH1.

As described earlier, the detection of the first conductive stripesprovided with high potential VH1 includes but is not limited to thedetection of potential, current or logic level. For example, in anexample of the present invention, high potential VH1 can be provided toone of the first conductive stripes (X1, X2, . . . , X8) via anextension resistor Re, and depressed intersecting regions can bedetermined by detecting the potential, current or logic level at one endof the extension resistor Re (between the extension resistor Re and theconductive stripe). High potential VH1 and low potential VL1 arerespectively provided on a first end of the first and second conductivestripes.

By determining a depressed intersecting region using potential P3detected by detecting unit V1, the second ends of the first conductivestripe and the second conductive stripe intersected in the depressedintersecting region are further respectively detected using detectingunits V6 and V7, wherein detecting units V1, V6, and V7 detects firstpotential P1, second potential P2, and third potential P3, respectively.Based on the impedance of extension resistor Re, first potential P1,second potential P2, and third potential P3, contact impedance R betweenthe first and second conductive stripes in the depressed intersectingregion can be determined. Thus, since the current in a series circuit isequal, (VH1−P3)/R1=(P1−P2)/R, and R=R1(P1−P2)/(VH1−P3).

As shown in FIG. 11C, when driving unit D1 provides high potential VH1and low potential VL1 to each intersecting region, depressedintersecting regions can be determined, so as impedance R between thefirst and second conductive stripes in each depressed intersectingregion.

Said driving unit D1 and detecting units V1, V6, and V7 include but arenot limited to being integrated in said driver 23 and detector 24,respectively, and the driving of driving unit D4 and detection ofdetecting units V4 and V5 include but are not limited to control bycontroller 25. Control of selector 22, driver 23, and detector 24 bycontroller 25 includes but is not limited to: directly or indirectly viaan extension resistor providing high and low potentials to a first endof at least one first conductive stripe and a first end of at least onesecond conductive stripe, respectively; detecting the signal between thestripe and the extension resistor; and detecting the potentials at thesecond ends of one of the first conductive stripes and one of the secondconductive stripes, respectively. Depression of a single object maysimultaneously depress several neighboring intersecting regions, asshown in FIG. 12C. Thus, the distances between the contact points in theneighboring intersecting regions can be used to determine whether theyare caused by the same object. For example, if the distance between thecontact points in two neighboring intersecting regions on the same axisdoes not exceed the width of one intersecting region, these contactpoints are regarded as caused by the depression of the same object.Similarly, if the distance between the contact points in twointersecting regions at diagonal positions does not exceed the diagonalwidth of one intersecting region, these contact points are regarded ascaused by the depression of the same object. The present inventionincludes but not is not limited these.

In addition, contact impedances R between the first and secondconductive stripes in neighboring intersecting regions depressed by thesame object are regarded as contact impedances connected in parallel andas the total contact impedance of the depression from the same object.For example, two neighboring intersecting regions are depressed by thesame object, the contact impedances at the contact points between thefirst and second conductive stripes in the two neighboring intersectingregions are Ra and Rb, respectively, and the total contact impedance ofthe depression is 1(RaRb/Ra+Rb). Accordingly, depression trajectory ofan object can be traced by the parallel contact impedances of theneighboring intersecting regions. For example, when a finger depressesthe device, the difference between the total contact impedances of adepressed single intersecting region and multiple neighboring depressedintersecting regions is not significant, thus it can be used todetermine whether neighboring depressed intersecting regions aredepressed by the same finger. For example, when two fingers are closerto each other, respective depressions can be distinguished by previousimpedance values of the depressions made by the two fingers.

For example, when depressed intersecting regions of a first subsequentdepression corresponding to a first depression and of a secondsubsequent depression corresponding to a second depression are adjacentto each other, these two depressions can be determined to be not made bythe same finger based on the total contact impedance of the firstdepression and that of the second depression. For example, thedetermination can be done based on the direction of movement of thefirst and second subsequent depressions and the total contactimpedances, or using a dividing algorithm based on the contact impedanceof each depressed intersecting region. For example, the determinationcan be done using a dividing algorithm based on weights generated fromthe contact impedance of each contact point, wherein the weight isinversely proportional to the contact impedance. It should be apparentto those skilled in the art that there are other ways of determiningdifferent depressions made in neighboring intersecting regions; thepresent invention is not limited to those described herein.

In an example of the present invention, the total contact impedances ofthe depressed intersecting regions can be used to determine whetherthere is a single depression or multiple depressions. In addition, whenit is determined that there are two depressions, two contact points thatare furthest from each other can be regarded as the positions of the twodepressions, respectively.

As shown in FIG. 12A, when a hand holds a pen to write on sensor, thedepression 122 made by the end of the pen has a small area, and thus thecontact impedance of the contact point between the first and secondconductive stripes is large. Conversely, the palm may have make one morepalm depressions 124, which have relatively larger areas, and thus thecontact impedances of the contact points between the first and secondconductive stripes are relatively small. Therefore, the palm depressions124 can be clearly identified.

Similarly, as shown in FIG. 12B, when a finger depresses sensor 21, thepalm will also make depressions. The area of finger depression 126 issmaller than those of palm depressions 124. Therefore, the palmdepressions 124 can be clearly identified. Accordingly, depressions of apen, a finger and a palm can be distinguished based on contactimpedances R between first and second conductive stripes at thedepressions using different threshold values.

In addition, the calculation of contact impedances R can be performedbefore or after the detection of contact points. Since the detection ofpotential values take longer, if the calculation of contact impedances Ris performed before the detection of contact points, then only contactpoints that are not made by palm depressions will need to be detected,thus eliminating the detection of potential values for palm contactpoints, which increases efficiency. Furthermore, the coordinates of adepression can be calculated by the coordinates of the center of mass ofthe contact points for that depression.

According to the descriptions given with respect to FIGS. 11A and 11C,in an example of the present invention, when determining whether eachintersecting region is depressed, contact impedances of the depressedintersecting regions are also determined, and the total contactimpedance for each depression of an object is determined based on thedepressed intersecting regions for that depression. For example, whetherintersecting regions are adjacent to one other is used for determiningif they are caused by the same depression, and parallel contactimpedances of the depressed intersecting regions of the same depressionis used as the total contact impedance, and the contact points of thedepressed intersecting regions of the same depression is used todetermine the position of the depression. In addition, consecutivedepressions made by the same object can be traced according to the totalcontact impedance of neighboring intersecting regions. Since that thetotal contact impedances made by the same moving object are similar, soif the total contact impedances detected at different timings aresimilar and the positions of depressions are within a predeterminedranges, these depressions can be considered as a set of continuousdepressions made by the same object. Thus, the depression trajectory ofa particular object can be traced by the total contact impedance in eachdepression of a set of continuous depressions made by the same object.

In another example of the present invention, depressed intersectingregions can be omitted based on their total contact impedances, and thecontact points of these depressed intersecting regions need not bedetected. For example, when at least a portion of a palm makes adepression, the palm depression can be identified and omitted based onthe total contact impedance it causes. Thus, when writing with a pen ora finger, depressions made by the pen or the finger can be distinguishedfrom that made by the palm, and only the positions of the pen/finger areof concern, i.e. detected. The trajectory of the pen/finger can betraced based on the total contact impedance of each depression in a setof continuous depressions made by the pen/finger. Herein, the presentinvention distinguishes depression from light contact by determiningwhether the conductive stripes are depressed.

In another example of the present invention, as shown in FIG. 13, adevice for position detection including a piezoelectric layer isdisclosed, which includes a first insulating layer 131, a firstconductive stripe layer 132, a piezoelectric layer 133, a secondconductive stripe layer 134 and a second insulating layer 135. The firstand second conductive stripe layers 132 and 134 respectively includessaid first and second conductive stripes. The piezoresistive layer 133is insulating when under no pressure, i.e. exhibits large impedance, andwhen under pressure, its impedance decreases or even becomes aconductor. The piezoresistive layer 133 can thus replace said insulatingspacers. When under pressure, the piezoresistive layer 133 can create anequivalent contact point due to lowered impedance.

Moreover, before the piezoresistive layer becomes a conductor, it isinsulating, and capacitive contact detection can be performed. In apreferred example of the present invention, mutual-capacitive contactdetection is employed. Thus, multiple light contacts can be detectedwhile the piezoresistive is insulating. For example, one can detectwhich intersecting regions are contacted. In addition, when thepiezoresistive layer becomes a conductor due to depression,aforementioned depression-type detection can be performed. Therefore,one can determine which intersecting regions are contacted and whichintersecting region are depressed. Thus, a comparison can be madebetween contacted intersecting regions detected by capacitive contactdetection and depressed intersecting regions detected by depression-typedetection for position detection or palm omission. For example, onlyintersecting regions that are detected by both the capacitive anddepression-type detections are subject to the determination of contactpoints. Further, for example, when an insulating pen is used,intersecting regions that are only detected by depression-type detectionbut not by capacitive detection are subject to the determination ofcontact points.

Accordingly, two or more multiple depression detection techniques can becombined to omit or eliminate the depressions made by a palm andidentify the depressions made by a pen. For example, a capacitivedetection and an infrared detection can be combined to performdepression detection with the palm omission function mentioned before.Thus, the present invention includes but is not limited to performingtwo or more contact or depression detections using the same sensor 21,or performing a plurality of contact or depression detections using aplurality of sensors 21. Palm omission or elimination can also beachieved based on the detection results from different contact ordepression detections. The plurality of sensors may include but notlimited to IR, capacitive, piezoresistive, camera-type or optical, SAWsensors.

In other words, the present invention provides a method and device foromitting palms using multiple positions detection, which includes but isnot limited to defining an omitted area on a second type ofcontact/depression detection using a first type of contact/depressiondetection, wherein the omitted area may include a plurality ofindependent omitted areas. For example, an omitted area is defined bycontacted intersecting regions detected by capacitive detection, andthen those contacts in the omitted area that are further detected byoptical (e.g. infrared) detection are regarded as do not exist.

In a preferred example of the present invention, a first type ofdetection is one that detects multiple contacts or depressions. Forexample, mutual-capacitive detection is performed on projectivecapacitive sensors to detect a plurality of contacted intersectingregions. An omitted area is then defined based on each contactedintersecting regions, for example, by expanding a certain range fromeach contacted intersecting region. For example, a contactedintersecting region is determined based on the capacitance changebetween a first and a second conductive stripe in an intersectingregion. Alternatively, mutual-capacitive detection can be performedusing sensors 21 described earlier, which treats all contactedintersecting regions as omitted areas. The mutual-capacitive detectiondetermines contacted intersecting regions based on signal changesdetected in each conductive stripe in a second axis when providing adriving signal to each conductive stripe in a first axis.

Alternatively, depression detection can be performed using saiddepression-type sensors, and then omitted areas can be defined based ondepressed intersecting regions or contact points, wherein the omittedareas can be expanded to include non-depressed intersecting regionsadjacent to the depressed intersecting regions based on the contactimpedances of the depressed intersecting regions. For example, alldepressed intersecting regions are defined as omitted areas, and thecontact impedance of each depressed intersecting region is determined,and when the contact impedance of any depressed intersecting regionfalling within a range (e.g. smaller than a certain threshold),intersecting regions adjacent to the depressed intersecting regions withcontact impedances fall within the range are also considered as omittedareas. Furthermore, the present invention further includes eliminatingdepressed intersecting regions or contact points depressed by apen/finger from depressed intersecting regions based on the contactimpedances of these depressed intersecting regions, and then definingthe omitted areas in any of the above manners.

Referring to FIGS. 4A and 14, intersecting regions A, B, and C aresimultaneously depressed. When high potential VH1 and low potential VL1are respectively provided to a first conductive stripe and a secondconductive stripe in intersecting region D, even though intersectingregion D is not depressed, current will flow from the first conductivestripe of intersecting region D via intersecting region A, B, and C tothe second conductive stripe of intersecting region D, which forms aconduction path, and causing misjudgment of intersecting region D as adepressed intersecting region.

In addition, based on the method for detecting contact points describedwith respect to FIG. 6A, when high potential VH1 and low potential VL1are respectively provided to both ends of a conductive stripe inintersecting region D, intersecting regions A, B, and C are at equalpotential, so the position of contact point may be misjudged as locatedin intersecting region B. Accordingly, the present invention provides amethod and device for detecting position misjudgment, which may omit oreliminate contact points that fall outside the detected intersectingregions during the detection of contact points of depressed intersectingregions. In an example of the present invention, the controller does notoutput position of any contact point that falls outside a detectedintersecting region. It should be apparent to those skilled in the artthat the determination of a contact point that falls within a detectedintersecting region is performed within a tolerance range, for example,a contact point falls outside a certain range expanded from a depressedintersecting region will be eliminated or omitted. In an example of thepresent invention, the eliminated or omitted depressions may include aplurality of contact points, wherein at least one contact point fallsoutside the tolerance range. In another example of the presentinvention, the eliminated or omitted depressions may include a pluralityof contact points, wherein all of the contact points fall outside thetolerance range. In an example of the present invention, intersectingregions A and B may be depressed by a palm, which cause misjudgment ofintersecting region D. Thus, the above omission or elimination ofmisjudged contact points or depressed intersecting regions is in otherwords an application of palm omission or omission of palm depressions.

In an example of the present invention, the determination of contactpoints of detected depressed intersecting regions can be achieved by oneaxial position determination, that is, the determination can be achievedwhile detecting a first one-dimensional coordinate Px, so there is noneed to detect a second one-dimensional coordinate Py.

Accordingly, in an example of the present invention, a filter procedureis further included, which can be performed by said controller. Thefiltering procedure includes determination of depressions to beeliminated among the depressions. Depressions to be eliminated will needto meet at least one of the following conditions: the total contactimpedance is smaller than a threshold value as described before; and theposition of at least one contact point in all contact pointscorresponding to the same depression falls outside the tolerance rangeof a corresponding intersecting region. In addition, the filteringprocedure further includes determining every non-eliminated depressionpositions among all the depressions, wherein the position of eachdepression is determined based on the position of the contact point ofthe depressed intersecting region corresponding to the same depression.

In the above descriptions, the determination of contact impedances canbe performed at the same time as the detection of depressed intersectingregions, that is, before the detection of contact points. Thus, by thefiltering procedure above, the detection of contact points can bereduced significantly. Therefore, in an example of the presentinvention, the determination of contact impedances is performed beforethe detection of contact points, and in the filtering procedure, thedetermination of total contact impedances that are smaller than somethreshold values is performed before the detection of contact points. Inother words, in the filtering procedure, the determination of the totalcontact impedances that are smaller than some threshold values is firstperformed, and then it is determined whether the, position of at leastone contact point in all contact points corresponding to the samedepression falls outside the tolerance range of a correspondingintersecting region.

In another example of the present invention, in the filtering procedure,it is first determined whether the position of at least one contactpoint in all contact points corresponding to the same depression fallsoutside the tolerance range of a corresponding intersecting region, andthen it is determined whether the total contact impedances are smallerthan the threshold values. In other words, the determination of contactpoints is first performed, and after misjudgments are eliminated, thosedepressions with the total contact impedances smaller than the thresholdvalue are eliminated, for example, palm omission.

Referring to FIG. 15A, when a pen depresses the sensors, based onpotential Vp detected by detecting unit V2 as described before withrespect to FIG. 6A, the position of depression detected is at depressionposition P, which is the same as the actual depression made by the pen.Referring to FIG. 15B, when a palm depresses several neighboringconductive stripes, the palm depressions may create total contactimpedance Rpalm across several conductive stripes (on the same layer),so when attempting to detect the depression position P of the pen, totalcontact impedance Rpalm may generate error in the detection ofdepression position P.

Referring to FIGS. 16A and 16B and the descriptions with respect to FIG.6A, the present invention provides a method and device for correctingposition detection error. First, as shown in step 1610, an extensionresistor Re is provided to electrically couple a conductive stripe tocreate a driven conductive stripe, and first high potential VH5 andfirst low potential VL5 are respectively provided to both ends of thedriven conductive stripe. Further, in step 1620, a non-depressedpotential between the extension resistor Re and the conductive stripe isdetected when the driven conductive stripe is not driven. Then, as shownin step 1630, a depressed potential between the extension resistor Reand the conductive stripe is detected when the driven conductive stripeis driven. Thereafter, as shown in step 1640, another conductive stripeis selected as a conductive stripe to be detected. Next, as shown insteps 1650 and 1660, second high potential VH2 and second low potentialVL2 are respectively provided to the detected conductive stripe, and apotential is detected via a conductive stripe depressed against thedetected conductive stripe. Next, as shown in step 1670, based on thenon-depressed potential, the depressed potential, and the detectedpotential, the position of a contact point on a depressed intersectingregion is determined, such as said first one-dimensional coordinate Pxor second one-dimensional coordinate Py.

First high potential VH5 and first low potential VL5 are respectivelyprovided by a driving unit D5. In an example of the present invention,Said driving units D2 and D5 and detecting units V2 and V8 include butare not limited to being integrated in said driver 23 and detector 24,respectively, and the driving of driving units D2 and D5 and detectionof detecting units V2 and V8 include but are not limited to control bycontroller 25. Control of selector 22, driver 23, and detector 24 bycontroller 25 includes but is not limited to: directly or indirectly viaan extension resistor respectively providing high and low potentials toa first end and second end of the same conductive stripe; directly orindirectly via an extension resistor respectively providing high and lowpotentials to a first end of at least a first conductive stripe and afirst end of at least one second conductive stripe; detecting the signalbetween the conductive stripe and the extension resistor; and when highand low potentials are provided to one of a pair of depressed conductivestripes, potentials of one or both ends of the other one of the pair ofdepressed conductive stripes are detected, wherein when high and lowpotentials are respectively provided to the first and the second ends ofthe same conductive stripe via the extension resistor, a non-depressedpotential and a depressed potential are determined based on the signalbetween the conductive stripe and the extension resistor.

Referring to FIGS. 17A and 17B, in an example of the present invention,the impedances of the extension resistor and the detected conductivestripe are Re and R, respectively. The first high potential and thefirst low potential are indicated by Vdd and ground potential,respectively, wherein the ground potential is 0 at default. When only apen depresses at location P, the impedance between the pen depressionlocation and the extension resistor is Rc. Since the pen depression hasno significant effect on the overall impedance, the overall impedanceremains almost the same with the status before depression, that is, thedepressed potential between the extension resistor and the conductivestripe is about the same as the non-depressed potential Vu. Whenimpedance Rpalm of depressions (e.g. palm depressions) across conductivestripes (across conductive stripe on the same layer) is detected, thecorrect location is location C, the impedance of the conductive stripeis Rp, and the depressed potential is Vd. In addition, the detection oflocation P is based on potential Vp detected by detecting unit V2.

From the above, the following equations can be obtained. Referring toFIG. 17A,

$\frac{Vu}{Vdd} = {{\frac{R}{{Re} + R}->\frac{Vdd}{Vu}} = {{{1 + \frac{Re}{R}}->\frac{Re}{R}} = \frac{{Vdd} - {Vu}}{Vu}}}$

Referring to FIG. 17B,

$\frac{Vd}{Vdd} = {{\frac{Rp}{{Re} + {Rp}}->\frac{Vdd}{Vu}} = {{{1 + \frac{Re}{R}}->\frac{Re}{R}} = \frac{{Vdd} - {Vu}}{Vu}}}$

In addition,

$\frac{Vp}{Vdd} = {\frac{{Rp} - {Rc}}{Rp} = {{{1 - \frac{Rc}{Rp}}->\frac{Rc}{Rp}} = {{1 - \frac{Vp}{Vdd}} = \frac{{Vdd} - {Vp}}{Vdd}}}}$${Rc} = {{Rp} \cdot \frac{{Vdd} - {Vp}}{Vdd}}$

Referring to FIG. 17A again,

$\begin{matrix}{\frac{Vc}{Vdd} = \frac{R - {Rc}}{R}} \\{= \frac{R - {{Rp} \cdot \frac{{Vdd} - {Vp}}{Vdd}}}{R}} \\{= {1 - {{Rp} \cdot \frac{{Vdd} - {Vp}}{Vdd}}}} \\{= {1 - {\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{Vd}{{Vdd} - {Vd}} \cdot \frac{{Vdd} - {Vp}}{Vdd}}}}\end{matrix}$${\overset{\circ}{V}c} = {{{Vdd} - {\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{{Vd} \cdot \left( {{Vdd} - {Vp}} \right)}{{Vdd} - {Vd}}}} = {{Vp} + {\Delta \; V}}}$$\begin{matrix}{{\Delta \; V} = {{Vdd} - {\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{{Vd} \cdot \left( {{Vdd} - {Vp}} \right)}{{Vdd} - {Vd}}} - {Vp}}} \\{= {\left( {{Vdd} - {Vp}} \right) - \frac{{Vd} \cdot \left( {{Vdd} - {Vp}} \right)}{{Vdd} - {Vd}}}} \\{= {\left( {{Vdd} - {Vp}} \right)\left( {1 - {\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{Vd}{{Vdd} - {Vd}}}} \right)}} \\{= {\left( {{Vdd} - {Vp}} \right) \cdot \frac{{{Vu} \cdot {Vdd}} - {{Vu} \cdot {Vd}} - {{Vdd} \cdot {Vd}} + {{Vu} \cdot {Vd}}}{{Vu} \cdot \left( {{Vdd} - {Vd}} \right)}}}\end{matrix}$${\Delta \; V} = {\left( {{Vdd} - {Vp}} \right) \cdot \frac{{Vdd}\left( {{Vu} - {Vd}} \right)}{{Vu} \cdot \left( {{Vdd} - {Vd}} \right)}}$

Compared to contact point C, when a depression across conductive stripesis closer to the lower potential,

${{Vc} = {{{Vdd} - {\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{{Vd} \cdot \left( {{Vdd} - {Vp}} \right)}{{Vdd} - {Vd}}}} = {{Vp} + {\Delta \; V}}}},$

that is, when the potential difference between the high and lowpotentials is known, based on the non-depressed potential Vu, thedepressed potential Vd, the detected potential Vp, the error in thedetected potential Vp can be corrected to create the correct detectedpotential Vc.

Similarly, when a depression across conductive stripes is closer to thehigher potential, as shown FIG. 17D, the following equations can beobtained.

$\frac{Vc}{Vdd} = \frac{{Rc}^{\prime}}{R}$$\frac{Vp}{Vdd} = {{\frac{{Rc}^{\prime}}{Rp}->{Rc}^{\prime}} = {{Rp} \cdot \frac{Vp}{Vdd}}}$$\frac{Vc}{Vdd} = {\frac{Rp}{R} \cdot \frac{Vp}{Vdd}}$ $\begin{matrix}{{Vc} = \frac{{Rp} \cdot {Vp}}{R}} \\{= {{Vp} \cdot \frac{{Vdd} - {Vu}}{Vu} \cdot \frac{Vd}{{Vdd} - {Vd}}}} \\{= {{Vp} - {Vp} + {{Vp} \cdot \frac{{Vdd} - {Vu}}{Vu} \cdot \frac{Vd}{{Vdd} - {Vd}}}}} \\{= {{Vp} + {{Vp} \cdot \left( {{\frac{{Vdd} - {Vu}}{Vu} \cdot \frac{Vd}{{Vdd} - {Vd}}} - 1} \right)}}} \\{= {{Vp} + {{Vp} \cdot \frac{{{Vdd} \cdot {Vd}} - {{Vu} \cdot {Vd}} - {{Vdd} \cdot {Vu}} + {{Vu} \cdot {Vd}}}{{Vu}\left( {{Vdd} - {Vd}} \right)}}}} \\{= {{Vp} + {{Vp} \cdot \frac{{Vdd}\left( {{Vd} - {Vu}} \right)}{{Vu}\left( {{Vdd} - {Vd}} \right)}}}} \\{= {{Vp} + {\Delta \; V^{\prime}}}}\end{matrix}$${\Delta \; V^{\prime}} = {{Vp} \cdot \frac{{Vdd}\left( {{Vd} - {Vu}} \right)}{{Vu}\left( {{Vdd} - {Vd}} \right)}}$

Compared to contact point C, when a depression across conductive stripesis closer to the higher potential,

${{Vc} = {{{Vp} + {{Vp} \cdot \frac{{Vdd}\left( {{Vd} - {Vu}} \right)}{{Vu}\left( {{Vdd} - {Vd}} \right)}}} = {{Vp} + {\Delta \; V^{\prime}}}}},$

that is, when the potential difference between the high and lowpotentials is known, based on the non-depressed potential Vu, thedepressed potential Vd, the detected potential Vp, the error in thedetected potential Vp can be corrected to create the correct detectedpotential Vc.

Furthermore, it can be seen from Vc=Vp+ΔV′ and

${{\Delta \; V^{\prime}} = {{Vp} \cdot \frac{{Vdd}\left( {{Vd} - {Vu}} \right)}{{Vu}\left( {{Vdd} - {Vd}} \right)}}},$

the amount of positional error is proportional to the position. That is,the proportion of positional error on a conductive stripe having contactimpedance that crosses intersecting regions can be determined from thenon-depressed potential Vu and the depressed potential Vd. Accordingly,in an example of the present invention, the proportion of positionalerror on a conductive stripe having contact impedance that crossesintersecting regions (crosses conductive stripes on the same layer) isdetermined based on the change in the potential at a position (e.g. thefirst end or second end) on the conductive stripe. In fact, knowing theproportion of positional error implies that the positional error is alsoknown. In other, words, the amount of positional error on a conductivestripe having contact impedance that crosses intersecting regions isbased on the change in the potential at a position (e.g. the first endor second end) on the conductive stripe.

From the descriptions above, compared to contact point C, when adepression across conductive stripes is closer to the higher potential,

${{Vc} = {\left( {{Vp} - {VL}} \right) - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}}},$

and when a depression across conductive stripes is closer to the lowerpotential,

${{Vc} = {\left( {{Vp} - {VL}} \right) - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}}},$

the proportion of error is

$\frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}.$

In other words, when detecting a contact point, the present inventioncorrects the error of the detected potential Vp based on thenon-depressed potential Vu and the depressed potential Vd to determinethe correct location C of the contact point.

In a best mode of the present invention, depressed conductive stripesare detected first, and then depressed intersecting regions aredetected, as indicated by previous descriptions with respect to FIGS. 4Ato 4C, 7 to 8C, 11A, and 11B. In addition, it further includes palmomission based on the total contact impedance as described earlier, andafter correction of positional error, position misjudgments areidentified and any misjudged depression is omitted or eliminated.Finally, the detection of contact points is carried out to determine thecoordinates of the center of mass of the contact point for eachdepression as the position of each depression.

The above examples are only used to illustrate the principles of thepresent invention, and they should not be construed as to limit thepresent invention in any way. The above examples can be modified bythose with ordinary skills in the arts without departing from the scopeof the present invention as defined in the following appended claims.

The foregoing description is not intended to be exhaustive or to limitthe invention to the precise forms disclosed. Obvious modifications orvariations are possible in light of the above teachings. In this regard,the embodiment or embodiments discussed were chosen and described toprovide the best illustration of the principles of the invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the inventions asdetermined by the appended claims when interpreted in accordance withthe breath to which they are fairly and legally entitled.

It is understood that several modifications, changes, and substitutionsare intended in the foregoing disclosure and in some instances somefeatures of the invention will be employed without a corresponding useof other features. Accordingly, it is appropriate that the appendedclaims be construed broadly and in a manner consistent with the scope ofthe invention.

1. A device for correcting position error, comprising: a sensorincluding a plurality of conductive stripes constituting a plurality ofintersecting regions, wherein a pair of depressed conductive stripesintersected in an intersecting region form a contact point due toelectrical contact so as to define a depressed intersecting region; adriver for providing a high potential and a low potential; a detectorfor detecting a signal of at least one conductive stripe; a selector foroperatively coupling the conductive stripes with the driver and thedetector; and a controller for controlling the driver, the detector andthe selector to perform at least the following operations: detectring anon-depressed potential at one end of each conductive stripe; detectringa depressed potential at the end of each conductive stripe; anddetermining a proportion of error at the contact point on each depressedconductive stripe based on the non-depressed potential and the depressedpotential.
 2. The device for correcting position error of claim 1,wherein the detection of the non-depressed potential and the depressedpotential comprises: sequentially selecting one of the conductivestripes as a driven conductive stripe; electrically coupling anextension resistor and the driven conductive stripe to form an extensionconductive stripe; providing high and low potentials to the extensionconductive stripe to detect the potential between the extension resistorand the driven conductive stripe as the non-depressed potential when theextension conductive stripe is not depressed; and providing high and lowpotential to the extension conductive stripe to detect the potentialbetween the extension resistor and the driven conductive stripe as thedepressed potential when the extension conductive stripe is depressed.3. The device for correcting position error of claim 2, wherein theproportion of error is$\frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)},$wherein VH, VL, Vd and Vu are respectively the high potential, the lowpotential, the depressed potential and the non-depressed potential. 4.The device for correcting position error of claim 1, wherein thecontroller further controls the driver, the detector and the selector toperform at least the following operations: detecting the position ofeach contact point, wherein when a contact impedance across conductivestripes on the same layer is detected at the depressed conductivestripes, the position is the non-corrected position including an errordue to the contact impedance across conductive stripes on the samelayer; and correcting the error according to the non-corrected positionand the proportion of error.
 5. The device for correcting position errorof claim 4, wherein the detection of position of the contact pointcomprises: sequentially selecting one and the other of each pair of theconductive stripes as a driven conductive stripe and a detectedconductive stripe, respectively; detecting the potential of the detectedconductive stripe as a detected potential when providing high and lowpotentials to both ends of the driven conductive stripe; and determiningthe position based on the detected potentials of the pair of depressedconductive stripes.
 6. The device for correcting position error of claim5, wherein the detection of position of the contact point comprises:electrically coupling an extension resistor and the driven conductivestripe to form an extension conductive stripe; providing high and lowpotentials to both ends of the extension conductive stripe to detect thepotential between the extension resistor and the driven conductivestripe as the non-depressed potential when the extension conductivestripe is not depressed; and providing high and low potentials to theextension conductive stripe to detect the potential between theextension resistor and the driven conductive stripe as the depressedpotential when the extension conductive stripe is depressed.
 7. Thedevice for correcting position error of claim 6, wherein when thecontact point on one of the pair of conductive stripes is locatedbetween the contact impedance across conductive stripes on the samelayer and the end being provided the high potential, the detectedpotential at the position on one of the pair of conductive stripes is${Vp} - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively. 8.The device for correcting position error of claim 6, wherein when thecontact point on one of the pair of conductive stripes is locatedbetween the contact impedance across conductive stripe on the same layerand the end being provided the low potential, the detected potential atthe position on one of the pair of conductive stripes is${Vp} - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively. 9.The device for correcting position error of claim 1, wherein thecontroller further controls the driver, the detector and the selector toperform the following operation of determining the pair of the depressedconductive stripes by determining whether there is a conducting pathbetween the conductive stripes in each intersecting region, wherein thedetection of the non-depressed potential is performed before thedetermination of the depressed conductive stripe.
 10. The device forcorrecting position error of claim 1, wherein the controller furthercontrols the driver, the detector and the selector to perform thefollowing operation of determining the depressed conductive stripes bydetermining whether there is a conducting path between each conductivestripe and any intersecting conductive stripe, wherein the conductivestripes are respectively located at a first and a second conductivestripe layers being intersected, and a plurality of insulating spacersare dispersed between the first and the second conductive stripe layers.11. A method for correcting position error, comprising: providing aplurality of intersecting regions constituted by a plurality ofintersecting conductive stripes, wherein a pair of depressed conductivestripes intersected in an intersecting region form a contact point dueto electrical contact so as to define a depressed intersecting region;detectring a non-depressed potential at one end of each conductivestripe when the conductive stripe is not depressed; detectring adepressed potential at the end of each depressed conductive stripe; anddetermining a proportion of error at the contact point on each depressedconductive stripe based on the non-depressed potential and the depressedpotential.
 12. The method for correcting position error of claim 11,wherein the detection of the non-depressed potential and the depressedpotential comprises: sequentially selecting one of the conductivestripes as a driven conductive stripe; electrically coupling anextension resistor and the driven conductive stripe to form an extensionconductive stripe; providing high and low potentials to the extensionconductive stripe to detect the potential between the extension resistorand the driven conductive stripe as the non-depressed potential when theextension conductive stripe is not depressed; and providing high and lowpotential to the extension conductive stripe to detect the potentialbetween the extension resistor and the driven conductive stripe as thedepressed potential when the extension conductive stripe is depressed.13. The method for correcting position error of claim 12, wherein theproportion of error is$\frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)},$wherein VH, VL, Vd and Vu are respectively the high potential, the lowpotential, the depressed potential and the non-depressed potential. 14.The method for correcting position error of claim 12, furthercomprising: detecting the position of each contact point, wherein when acontact impedance across conductive stripes on the same layer isdetected at the depressed conductive stripes, the position is thenon-corrected position including an error due to the contact impedanceacross conductive stripes on the same layer; and correcting the erroraccording to the non-corrected position and the proportion of error. 15.The method for correcting position error of claim 14, wherein thedetection of position of the contact point comprises: sequentiallyselecting one and the other of each pair of the conductive stripes as adriven conductive stripe and a detected conductive stripe, respectively;detecting the potential of the detected conductive stripe as a detectedpotential when providing high and low potentials to both ends of thedriven conductive stripe; and determining the position based on thedetected potentials of the pair of depressed conductive stripes.
 16. Themethod for correcting position error of claim 15, wherein the detectionof position of the contact point comprises: electrically coupling anextension resistor and the driven conductive stripe to form an extensionconductive stripe; providing high and low potentials to both ends of theextension conductive stripe to detect the potential between theextension resistor and the driven conductive stripe as the non-depressedpotential when the extension conductive stripe is not depressed; andproviding high and low potentials to the extension conductive stripe todetect the potential between the extension resistor and the drivenconductive stripe as the depressed potential when the extensionconductive stripe is depressed.
 17. The method for correcting positionerror of claim 16, further comprising: when the contact point on one ofthe pair of conductive stripes is located between the contact impedanceacross conductive stripes on the same layer and the end being providedthe high potential, the detected potential at the position on one of thepair of conductive stripes is${Vp} - {\left( {{Vp} - {VH}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively. 18.The method for correcting position error of claim 16, wherein when thecontact point on one of the pair of conductive stripes is locatedbetween the contact impedance across conductive stripe on the same layerand the end being provided the low potential, the detected potential atthe position on one of the pair of conductive stripes is${Vp} - {\left( {{Vp} - {VL}} \right) \cdot \frac{\left( {{VH} - {VL}} \right) \cdot \left( {{Vu} - {Vd}} \right)}{\left( {{Vu} - {VL}} \right)\left( {{VH} - {Vd}} \right)}}$after correction of positional error, wherein VP, VH, VL, Vd and Vu arethe detected potential, the high potential, the low potential, thedepressed potential and the non-depressed potential, respectively. 19.The method for correcting position error of claim 11, further comprisingthe following operation of determining the pair of the depressedconductive stripes by determining whether there is a conducting pathbetween the conductive stripes in each intersecting region, wherein thedetection of the non-depressed potential is performed before thedetermination of the depressed conductive stripe.
 20. The method forcorrecting position error of claim 11, further comprising the followingoperation of determining the pair of the depressed conductive stripes bydetermining whether there is a conducting path between the conductivestripes in each intersecting region, wherein the detection of thenon-depressed potential is performed before the determination of thedepressed conductive stripe.
 21. A method for correcting position errorduring handwriting, comprising: providing a plurality of intersectingregions constituted by a plurality of intersecting conductive stripes;determining a depression of a pen and a depression of a palm acrossconductive stripes on the intersecting regions; determining the positionof the depression of the pen, wherein on the conductive stripe which isdepressed simultaneously by the pen and the palm, an error in theposition of the depression of the pen is caused by the depression of thepalm across conductive stripes; and correcting the error when the pendepresses the conductive stripe depressed by the palm.
 22. The methodfor correcting position error during handwriting of claim 21, wherein apair of depressed conductive stripes intersected in an intersectingregion form a contact point due to electrical contact so as to define adepressed intersecting region, and the position of the depression of thepen is determined based on the position of at least one contact point,wherein the determination of the position of the contact pointcomprises: sequentially selecting one and the other of the pair ofdepressed conductive stripes as a driven conductive stripe and adetected conductive stripe, respectively; detecting the potential of thedetected conductive stripe as a detected potential when providing a highand a low potentials to both ends of the driven conductive stripe; anddetermining the position of the contact point based on the detectedpotentials of the pair of depressed conductive stripes.
 23. The methodfor correcting position error during handwriting of claim 22, whereinthe correction of the error comprises: detecting a non-depressedpotential at one end of the conductive stripe before the palm depressesthe conductive stripe; detecting a depressed potential at the end of theconductive stripe after the palm depresses the conductive stripe; andcorrecting the error based on the non-depressed potential, depressedpotential and the position of the contact point detected on theconductive stripe depressed by the palm.
 24. The method for correctingposition error during handwriting of claim 21, wherein the error iscorrected based on a proportion of error, and the determination of theproportion of error comprises: detecting a non-depressed potential atone end of each conductive stripe; detecting a depressed potential atthe end of each depressed conductive stripe; and determining theproportion of error on each depressed conductive stripe based on thenon-depressed potential and depressed potential.